Enrique's $5million ring for Anna

The tennis babe showed off the huge rock as the couple arrived at a radio station in Australia for an interview.

The pricey diamond came from the world's biggest mine, the Argyle, in north-west Australia, where the gems have a unique champagne and cognac colour.

Friends claim the Latin singer is finally ready to settle down with the Russian beauty, after being linked with a string of other women since they started dating in 2002.

Britain's Daily Star newspaper quotes a friend as saying: "His relationship with Anna has not always been smooth, but deep down they both absolutely adore each other. Giving an Anna such a beautiful diamond shows how much he loves her."

Last week, Anna slammed rumours their relationship was on the rocks, insisting: "Enrique's a lovely guy and my favourite singer."